The nurse explains that carpal tunnel syndrome is caused when the carpal tunnel compresses the:

Correct Answer: C

Rationale: Carpal tunnel syndrome results from compression within the wrist's carpal tunnel, a narrow passage housing tendons and the median nerve. This nerve, when squeezed by swelling or repetitive strain, causes numbness, tingling, and pain in the thumb and fingers. The radial artery supplies the hand but isn't in the tunnel. The brachial artery is in the upper arm, unrelated to wrist issues. The ulnar nerve runs outside the tunnel, affecting different fingers when compressed. The median nerve's location and symptoms align with the condition's hallmark, making it the clear cause, distinct from vascular or other nerve involvement.

Correct Answer: D

Rationale: The buccinator is the primary muscle of the cheek, forming its muscular foundation and aiding in chewing by compressing the cheek against the teeth. Located between the maxilla and mandible, it's essential for keeping food in the oral cavity. The masseter, a powerful jaw-closing muscle, is superficial to the cheek but not its main component. The temporalis elevates the mandible from above the cheek. The zygomaticus major lifts the mouth corners for smiling, not forming the cheek. The buccinator's role and position make it the correct answer, as it directly constitutes the cheek's structure, distinguishing it from other facial muscles involved in jaw or expression movements.

Correct Answer: A

Rationale: During inhalation, external intercostals contract to elevate the ribs, expanding the thoracic cavity for air intake, while the diaphragm also flattens. In forced exhalation, internal intercostals contract to depress the ribs, reducing cavity volume to expel air, often with abdominal muscle aid. Transverse abdominis assists exhalation but doesn't directly depress ribs. The diaphragm drives inhalation, not rib depression. Reversing intercostals is incorrect, as their roles are distinct. External intercostals for inhalation and internal for forced exhalation is the correct answer, reflecting their specific actions in respiratory mechanics, key to understanding breathing dynamics.

Correct Answer: A

Rationale: During inspiration, external intercostals act as synergists to the diaphragm, elevating the ribs to expand the thoracic cavity while the diaphragm flattens, increasing volume for air intake. External obliques and rectus abdominis compress the abdomen, aiding exhalation, not inspiration. Internal intercostals depress ribs in forced exhalation, opposing inspiration. External intercostals are the correct answer, as they assist the diaphragm's primary role in breathing, enhancing chest expansion, a critical synergy in respiratory mechanics.

Correct Answer: B

Rationale: Muscles are specialized tissues responsible for movement and are classified based on structure and function. The three distinct types are cardiac, smooth, and skeletal. Cardiac muscle powers the heart, contracting involuntarily to pump blood. Smooth muscle lines organs like the stomach and blood vessels, also working involuntarily to manage processes like digestion. Skeletal muscle, attached to bones, enables voluntary movements like walking or lifting. Tendons, ligaments, and joints are connective structures, not muscle types tendons link muscle to bone, ligaments connect bones, and joints are bone junctions. Flexion and extension describe movements, not muscle categories, and stringy isn't a scientific term for muscle. The correct classification reflects the histological and functional diversity of muscle tissue, critical for understanding their roles in the body, distinguishing them from structural or movement descriptors that don't define muscle itself.